This invention relates generally to vibrating concrete for compaction, vibrating screed bars for screeding, vibrating tools used for smoothing the concrete, tooling construction joints and edges and more particularly to gasoline engine powered vibrator for vibrating tools for finishing concrete.
Once concrete is placed, it is typically necessary to level the surface of the concrete, compact concrete, create construction joints, apply an edge finish to the concrete and finish the centers. The advantages of vibrating tools in finishing concrete are well known. Gasoline and electric powered vibrating screeds are commonly used for screeding and consolidating the concrete. Such screeds include a gasoline powered internal combustion engine or an electric powered motor coupled to an unbalanced shaft or eccentric which vibrates a metal bar which is used to strike off (remove excess) and smooth freshly poured concrete. Recently small internal combustion engines (between one and two horsepower) have begun to replace electric motors to power concrete vibrators that consolidate freshly placed concrete in walls, form structures, foundation slabs and the like. These small internal combustion engines are self contained and more portable than electric motors previously used to power concrete vibrators.
In recent years the small hand held gas powered engines have become popular for vibrating concrete to remove the air pockets created when placing the concrete. It is believed that sealed bearings may have been used for the vibrators while screeding concrete but these vibrators were not designed to be submerged in to the cement. When the designs were altered to submerge the gas-powered vibrators in cement the designers changed to oil bath lubrication from the sealed bearings because industry practice for submersible consolidation vibrators has been to provide oil bath lubrication for bearings in a submersible vibrator. Typically, submersible consolidation vibrators were powered by an electric motor. Electric powered vibrators that have been used for many years turn approximately 10,000 to 12,000 RPM. Oil bath lubricated bearings were used in electrically powered consolidation vibrators because of the high operating RPMs.
Vibrators used for screeding concrete (and with other concrete finishing tools) only need to turn at approximately 3,000 RPM. Small handheld gasoline engine generate 300 RPM at about one half throttle. When used for consolidating concrete (not screeding) the small engines are run at full throttle, i.e. about 6,000 RPM.
It is believed that when small gas-powered engines drive vibrators using an oil bath for lubrication additional torque is required to turn the eccentric as a result of added friction compared to a vibrator using sealed bearings. This in turn may severally limit the size of the eccentric used for vibration. Testing and research has established that the small gas-powered engines do not turn enough RPM to damage sealed bearings.
A vibratory power unit in accordance with the disclosure herein will contain one or more of the following features and limitation either alone or in combination, an internal combustion engine, a vibrator coupled to the internal combustion engine, a semi-rigid shaft case extending between the internal combustion engine and the vibrator and an isolation unit disposed between the internal combustion engine and the vibrator to reduce vibrations experienced by the internal combustion engine. A coupling configured to releasably couple the vibrator to a concrete finishing tool and to transfer vibration from the vibrator to the finishing tool may be provided. A handle may be coupled to the semi-rigid shaft whereby the user can control rotation of a concrete finishing tool coupled to the vibrator. The coupling may be configured to permit adjustment of the vertical angle between the finishing face of the concrete finishing tool and the longitudinal axis of the semi-rigid shaft case. The coupling may also be configured to permit adjustment of the horizontal angle between the concrete finishing tool and the longitudinal axis of the semi-rigid shaft case. The semi-rigid shaft case may include a first rigid shaft case portion and a second rigid shaft case portion with the isolation unit coupling the first rigid shaft case portion to the second rigid shaft case portion. Preferably, the vibrator utilizes sealed bearings. A plurality of vibrators of varying lengths and diameters may be provided for attachment to the semi-rigid shaft.
According to a second embodiment of the disclosure, a vibrating concrete tool includes one or more of the following limitations, alone or in combination, an internal combustion engine, a vibrator coupled to the internal combustion engine, a concrete finishing tool, a mount for mounting the internal combustion engine to the concrete finishing tool, an elongated handle for manipulating the concrete finishing tool and internal combustion engine as a unit and an attachment for coupling the handle to the finishing tool, said attachment permitting selective alteration of the vertical angle between the concrete finishing tool and the longitudinal axis of the handle. The mount is configured to couple the vibrator to the concrete finishing tool and to transfer vibrations from the vibrator to the concrete finishing tool. The mount is preferably configured to permit coupling of the attachment and the vibrator at substantially the same position between the ends of the concrete finishing tool. The mount may be configured to provide structural support to the concrete finishing tool. A remotely actuatable throttle control may be coupled to the engine. The remotely actuatable throttle control may be configured to control actuators powered, at least in part, by power scavenged from the engine magneto circuitry.
Additional features and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of illustrated embodiments exemplifying the best mode of carrying out the invention as presently perceived.